2 Answers
2

This isn't one particular vote. What is being said is that Thatcher sounds like a privileged Conservative wife, and they are already supporters of the Conservative party (so they have "their vote"), but she won't appeal to people from other parts of the voting public (e.g. Men, Non-Conservatives etc).

The ministers want someone with a wider appeal to gain a share of the vote.

I've not seen the movie, but its clear to me what is being referred to here.

The minister is referring to a generic type of voter, the "privileged Conservative wife". A married woman, relatively wealthy, who typically votes Conservative - very much like Margaret Thatcher herself, who will probably identify somewhat with her already.

The minister is letting Thatcher know that she needs to appeal to a broader range of British voters - not just ones that are going to vote for her anyway.